2002 Mercedes Benz C200

Computer problem
2002 Mercedes Benz C200 4 cyl Two Wheel Drive Automatic 149000 miles

My remote car key, does not always work anymore.I hv
changed battery, and it works intermitently. Where can I get this fixed. I am not sure if this problem relates to the key or the receiver in the car. How can I check this, or get help to fix it. I only have one key left and don't want to have to purchase a new key. Pls help.
January 16, 2009.

Many times MB keys just have contact issues with the battery. Remove the key battery an with a fine grit sandpaper scuff the battery contacts on the key not the battery. Often times this will remedy simple contact issues in these types of keys.

Jan 19, 2009.